/**
 * Software License, Version 1.0
 * 
 * Copyright 2003 The Trustees of Indiana University. All rights reserved.
 * 
 * 
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 * 
 * 1) All redistributions of source code must retain the above copyright notice,
 * the list of authors in the original source code, this list of conditions and
 * the disclaimer listed in this license; 2) All redistributions in binary form
 * must reproduce the above copyright notice, this list of conditions and the
 * disclaimer listed in this license in the documentation and/or other materials
 * provided with the distribution; 3) Any documentation included with all
 * redistributions must include the following acknowledgement:
 * 
 * "This product includes software developed by the Community Grids Lab. For
 * further information contact the Community Grids Lab at
 * http://communitygrids.iu.edu/."
 * 
 * Alternatively, this acknowledgement may appear in the software itself, and
 * wherever such third-party acknowledgments normally appear.
 * 
 * 4) The name Indiana University or Community Grids Lab or NaradaBrokering,
 * shall not be used to endorse or promote products derived from this software
 * without prior written permission from Indiana University. For written
 * permission, please contact the Advanced Research and Technology Institute
 * ("ARTI") at 351 West 10th Street, Indianapolis, Indiana 46202. 5) Products
 * derived from this software may not be called NaradaBrokering, nor may Indiana
 * University or Community Grids Lab or NaradaBrokering appear in their name,
 * without prior written permission of ARTI.
 * 
 * 
 * Indiana University provides no reassurances that the source code provided
 * does not infringe the patent or any other intellectual property rights of any
 * other entity. Indiana University disclaims any liability to any recipient for
 * claims brought by any other entity based on infringement of intellectual
 * property rights or otherwise.
 * 
 * LICENSEE UNDERSTANDS THAT SOFTWARE IS PROVIDED "AS IS" FOR WHICH NO
 * WARRANTIES AS TO CAPABILITIES OR ACCURACY ARE MADE. INDIANA UNIVERSITY GIVES
 * NO WARRANTIES AND MAKES NO REPRESENTATION THAT SOFTWARE IS FREE OF
 * INFRINGEMENT OF THIRD PARTY PATENT, COPYRIGHT, OR OTHER PROPRIETARY RIGHTS.
 * INDIANA UNIVERSITY MAKES NO WARRANTIES THAT SOFTWARE IS FREE FROM "BUGS",
 * "VIRUSES", "TROJAN HORSES", "TRAP DOORS", "WORMS", OR OTHER HARMFUL CODE.
 * LICENSEE ASSUMES THE ENTIRE RISK AS TO THE PERFORMANCE OF SOFTWARE AND/OR
 * ASSOCIATED MATERIALS, AND TO THE PERFORMANCE AND VALIDITY OF INFORMATION
 * GENERATED USING SOFTWARE.
 */
package cgl.narada.protocol;

import java.util.Hashtable;
import java.util.LinkedList;
import java.util.concurrent.locks.Condition;
import java.util.concurrent.locks.Lock;
import java.util.concurrent.locks.ReentrantLock;

import cgl.narada.event.NBEvent;
import cgl.narada.util.MutableInteger;

public class EventBuffer implements ProtocolDebugFlags {
    private final Lock lock = new ReentrantLock();

    private final Condition notEmpty = lock.newCondition();

    private LinkedList<NBEvent> eventBuffer;

    private int bufferSize = 0;

    private long totalPayloadSize = 0;

    private Hashtable<Object, MutableInteger> bufferInfoTable;

    private String moduleName = "EventBuffer: ";

    private static final EventBuffer instance = new EventBuffer();

    private EventBuffer() {
        eventBuffer = new LinkedList<NBEvent>();
        bufferInfoTable = new Hashtable<Object, MutableInteger>();
    }

    public static EventBuffer getInstance() {
        return instance;
    }
    
    
    protected void new_addEvent(NBEvent nbEvent) {
        lock.lock();
        try {
            totalPayloadSize += nbEvent.getContentPayloadSize();
            synchronized(eventBuffer) {
              eventBuffer.add(nbEvent);
              bufferSize++;
            }
              

            if (bufferSize == 1) {
                notEmpty.signal();
            }

            if (EventBuffer_Debug) {
                System.out.println(moduleName + "Buffer Size = "
                    + eventBuffer.size());
            }
        } finally {
            lock.unlock();
        }
        
    }

    protected NBEvent new_getEvent() throws InterruptedException {
        lock.lock();
        try {
            while (bufferSize == 0) {
                notEmpty.await();
            }

             
            synchronized(eventBuffer) {
                NBEvent nbEvent = eventBuffer.remove();
                bufferSize--;
            
            totalPayloadSize -= nbEvent.getContentPayloadSize();

            if (EventBuffer_Debug) {
                String report = moduleName + "Buffer Size = "
                    + eventBuffer.size();
                System.out.println(report);
            }

            return nbEvent;
            }
        } finally {
            
            lock.unlock();
        }
    }

    protected void addEvent(NBEvent nbEvent) {
        lock.lock();
        try {
            totalPayloadSize += nbEvent.getContentPayloadSize();
            eventBuffer.add(nbEvent);
            bufferSize++;

            if (bufferSize == 1) {
                notEmpty.signal();
            }

            if (EventBuffer_Debug) {
                System.out.println(moduleName + "Buffer Size = "
                    + eventBuffer.size());
            }
        } finally {
            lock.unlock();
        }
        
    }

    protected NBEvent getEvent() throws InterruptedException {
        lock.lock();
        try {
            while (bufferSize == 0) {
                notEmpty.await();
            }

            NBEvent nbEvent = eventBuffer.removeFirst();
            bufferSize--;
            totalPayloadSize -= nbEvent.getContentPayloadSize();

            if (EventBuffer_Debug) {
                String report = moduleName + "Buffer Size = "
                    + eventBuffer.size();
                System.out.println(report);
            }

            return nbEvent;
        } finally {
            lock.unlock();
        }
    }

    /**
     * This returns the number of events in a given buffer.
     * 
     * @return
     */
    public int getNumberOfEventsInBuffer() {
        return bufferSize;
    }

    /**
     * This returns the total payload size of ALL the events in the buffer
     * 
     * @return
     */
    public long getTotalPayloadSize() {
        return totalPayloadSize;
    }

}
